When to Plant Broccoli in Zone 4

Brassica oleracea var. italica

Last updated: May 15, 2026 · Sources: USDA, NOAA, Cooperative Extension
Action Plan

Plant Broccoli in Zone 4

  • Start indoors: Mar 22
  • Transplant: May 10 — after last frost (May 10)
  • First harvest: Jul 16 (60–90 days)
⚠️ Don't plant before last frost (May 10) — cold snaps kill young transplants.
Last frost
May 10
First frost
Sep 25
Growing season
138 days
Quick Facts
Sunlight ☀️ Full Sun
Water Needs 💧💧 Moderate
Spacing 18 inches apart
Planting Depth 0.5 inch
Min Soil Temp 40°F
Germination 5–10 days
Days to Maturity 60–90 days
Frost Tolerance Moderate frost tolerance
Soil pH 6.0–7.0
Difficulty Moderate
What you'll need — Zone 4
🛒 Broccoli — Seeds & Supplies
  • 🌱 Broccoli Seeds
  • 🌱 Transplant Fertilizer
  • 🌱 Garden Row Cover

Search for these at your local garden center or nursery.

Growing Tips

  • Start indoors 6–8 weeks before transplanting.
  • Harvest the main head before flowers open.
  • After cutting main head, side shoots continue to produce for weeks.
  • Broccoli is cold-tolerant — a light frost makes it sweeter.
  • Feed with nitrogen-rich fertilizer early, then switch once heads form.

Common Mistakes

  • Letting the head flower — once yellow, it's bitter and woody.
  • Transplanting in warm weather — broccoli bolts in heat.
  • Skipping side shoot harvesting after the main head.
  • Planting too close — needs 18 inches between plants.

Companion Planting

Companion planting improves growth, deters pests, and makes better use of garden space.

✓ Good Companions

Onion Celery Potato

✗ Avoid Nearby

Tomato Strawberry

Broccoli Schedule — All Zones

ZoneStart IndoorsTransplant Direct SowHarvest StartHarvest End
Zone 3 Mar 27 May 15 — Jul 21 Sep 12
Zone 4 Mar 22 May 10 — Jul 16 Sep 14
Zone 5 Mar 12 Apr 30 — Jul 6 Sep 4
Zone 6 Feb 25 Apr 15 — Jun 21 Aug 20
Zone 7 Feb 15 Apr 5 — Jun 11 Aug 10
Zone 8 Jan 30 Mar 20 — May 26 Jul 25
Zone 9 Jan 10 Feb 28 — May 6 Jul 5
Zone 10 Dec 23 Feb 10 — Apr 18 Jun 17
Zone 11 Dec 17 Jan 15 Jan 15 Mar 23 May 22
📚 Data Sources
Frost dates: NOAA Climate Normals 1991–2020, National Centers for Environmental Information.
Hardiness zones: USDA Plant Hardiness Zone Map, Agricultural Research Service.
Growing requirements: Cooperative Extension Services — NC State, Penn State, University of Florida IFAS.
Companion planting: Cornell University Cooperative Extension.
Data compiled from public agricultural sources. Always verify with your local extension office for micro-climate adjustments.